In the study conducted in the present research hydrogen storage properties of pristine and Lidecorated BC6N monolayer are considered by first-principles calculations. It is predicted that the double-sided Li-decorated monolayer of BC6N will reach a suitable substrate that adsorbs up to eight molecules of H2 with hydrogen storage capacities of 12.60 wt% and adsorption energies within in the range of 0.23–0.29 eV. Hydrogen desorption from 2Li/BC6N (8H2) system can occur at TD = 297 K and P = 1 atm which is at the ambient conditions. Potential usage of 2Li/BC6N adsorptive medium for practical hydrogen storage purposes is concluded from the results of the present study.